Phase scanned microstrip array antenna

Abstract

A microstrip array antenna, including spaced radiator elements supplied w microwave power and separated from an underlying ground reference plane by a layer of dielectric material, in which the antenna beam is phase scanned by periodically closing switching devices connected between the reference plane and at least one null point of each radiator element. In one embodiment, the radiator elements are identical rectangular patches disposed along a path, each patch having a length parallel to the path of one-half wavelength and a width transverse to the path not exceeding one wavelength in the underlying dielectric material at the antenna operating frequency. The patches are connected in series to receive microwave power by conductive strip elements whose widths are selected to effect a desired distribution of radiated microwave power from the patches.

What is claimed and desired to be secured by Letters Patent of the United States is: 
     
       1. A microstrip array antenna, comprising: an electrically conductive reference surface;   a layer of dielectric material overlying said reference surface;   a plurality of electrically conductive, spaced apart, radiator elements overlying said layer of dielectric material, each radiator element including at least one radiating edge, and each radiator element having an effective dimension transverse to said radiating edge of approximately one-half wavelength, or a multiple of one-half wavelength, in the underlying dielectric material at a predetermined antenna operating frequency;   microwave supply means for supplying microwave energy to each radiator element at said antenna operating frequency; and   scanning means for phase scanning the antenna beam, comprising: a plurality of switching means associated respectively with said radiator elements, each switching means being connected between a null point of the associated radiator element and the reference surface, and   switch control means for periodically closing and opening said plurality of switching means.     
     
     
       2. An antenna, as described in claim 1, wherein: said radiator elements are disposed along a longitudinal path; and   each radiator element comprises two parallel radiating edges which are spaced apart by substantially one-half wavelength in the underlying dielectric material at the antenna operating frequency and which extend transversely of the longitudinal path.   
     
     
       3. An antenna, as described in claim 2, wherein each radiator element is a rectangular element having a transverse width which does not exceed one wavelength at the antenna operating frequency in the underlying dielectric material. 
     
     
       4. An antenna, as described in claim 3, wherein said radiator elements have identical transverse and longitudinal dimensions. 
     
     
       5. An antenna, as descirbed in claim 4, wherein said microwave supply means comprises: a plurality of electrically conductive transmission line elements overlying said layer of dielectric material, for interconnecting said radiator elements in series along said path, each transmission line element being connected to supply microwave energy from one radiator element to a subsequent radiator element; and   an electrically conductive input means overlying said layer of dielectric material, for supplying microwave energy to a first one of said radiator elements;   wherein the widths of said transmission line elements are selected to effect a desired distribution of radiated microwave power from the plurality of radiator elements.   
     
     
       6. An antenna, as described in claim 2, wherein said plurality of switching means comprises a plurality of pairs of switching devices associated respectively with said radiator elements, the switching devices of each pair being connected between said reference surface and respective null points on opposite longitudinal sides of the associated radiator element. 
     
     
       7. An antenna, as described in claim 6, wherein said switching devices are PIN diodes. 
     
     
       8. A microstrip array antenna, comprising: an electrically conductive reference surface;   a layer of dielectric material overlying said reference surface;   a plurality of electrically conductive rectangular radiator elements overlying said layer of dielectric material and spaced apart along a longitudinal path, said radiator elements having identical widths transverse to said path and having identical lengths parallel to said path; and   microwave supply means for supplying microwave energy to each radiator element at a predetermined antenna operating frequency, including: an electrically conductive input element overlying said layer of dielectric material, for supplying microwave energy to a first one of said radiator elements,   a plurality of electrically conductive transmission line elements overlying said layer of dielectric material, for interconnecting said radiator elements in series along said path, each transmission line element being connected to supply microwave energy from one radiator element to a subsequent radiator element, the widths of said transmission line elements being selected to effect a desired distribution of radiated microwave power from the plurality of radiator elements.     
     
     
       9. An antenna, described in claim 8, wherein each radiator element has a length parallel to said path of approximately one-half wavelength at the antenna operating frequency in the underlying dielectric material and has a width transverse to said path not exceeding one wavelength at the antenna operating frequency in the underlying dielectric material. 
     
     
       10. An antenna, as described in claim 9, which further includes scanning means for phase scanning the antenna beam, comprising: a plurality of switching means associated respectively with said radiator elements, each switching means being connected between a null point of the associated radiator element and the reference surface; and   switch control means for periodically closing and opening said plurality of switching means.   
     
     
       11. A microstrip array antenna, comprising: an electrically conductive reference surface;   a layer of dielectric material overlying the reference surface;   a plurality of electrically conductive, radiator elements overlying the layer of dielectric material and space apart along a longitudinal path, each radiator element comprising two transversely extending parallel radiating edges which are spaced apart by substantially one-half wavelength in the underlying dielectric material at a predetermined antenna operating frequency and which define a null axis which extends transversely equidistant from the two radiating edges;   microwave supply means for supplying microwave energy to each radiator element at the predetermined antenna operating frequency; and   scanning means for phase scanning the antenna beam, comprising: a plurality of pairs of switching means associated respectively with the radiator elements, the switching means of each pair being connected between the reference surface and respective null points along the null axis on opposite longitudinal sides of the associated radiator element; and   switch control means for periodically closing and opening the switching means.